This Spanish-language manual, developed for training Peace Corps volunteers for service in Spanish-speaking developing countries, explains the process of agricultural extension and provides practical guidance on carrying out an extension program. The first of six chapters explains what agricultural extension is and how it is used in the Peace Corps. The second and third chapters concentrate on background information for beginning and carrying out an agricultural extension program. Information is given on resources, planning, recordkeeping, and providing direct and indirect services to farmers. In the fourth chapter, suggestions for conducting farmer training are given, with emphasis on teaching methods and materials. The fifth chapter explains how to organize a farm cooperative, including group dynamics, leader training, and defining issues and tasks. In the final chapter, management and evaluation of an agricultural extension program are discussed. Appendixes to the manual present comparative case studies, information on technical manuals and extension training, and an 11-item bibliography and resource list. (KC)